Adding Ca to the calcareous sand did not increase the concentration of Ca in the leaf tissue of either species (Table 1). Adding Ca to Kentucky bluegrass on calcareous sand did not increase the clipping yield, but adding CaCO₃ to creeping bentgrass on calcareous sand increased clipping yield by 18% (Table 1). Adding any Ca source to creeping bentgrass grown on silica sand increased the concentration of Ca measured in the leaf tissue. Only CaCO₃ and calcium chelate increased the leaf Ca concentration of Kentucky bluegrass grown on silica sand. But, these increased Ca concentrations did not exceed the amount of Ca found in grasses growing on the calcareous sand control (Table 1). Adding gypsum to grasses grown on silica sand increased the clipping weight of Kentucky bluegrass by 22% and creeping bentgrass by 32% (Table 1). This indicates the calcareous sand is supplying the amount of Ca required for plant growth and that Kentucky bluegrass and creeping bentgrass grown on silica sand would benefit from additional applications of Ca.

Creeping bentgrass leaf Mg concentration was greatest for grass that was grown on the calcareous control. Calcium nitrate applications to creeping bentgrass reduced Mg levels on both silica sand and calcareous sand. This effect was not noticed on Kentucky bluegrass. Due to the fact that sand has a limited cation exchange capacity, additional Ca may cause the other basic cations, like Mg, to be removed from exchange sites. In solution, Mg could be readily lost either by leaching out of the soil profile or by precipitation into insoluble forms, which may cause the plants to have lower tissue Mg levels.

The CaCO₃ and gypsum were applied granularly using "SuperCal 98-G" CaCO₃ and "SuperCal SO₄" gypsum from Calcium Products, Inc., Gilmore City, IA 50541. Both sources are finely ground to increase reactivity and re-pelletized to aid in handling and distribution. The Ca(NO₃)₂ and the calcium chelate were sprayed onto the plots. Liquid urea was also sprayed at a N rate of 3.7 g•m^-2 to balance the amount of N that the Ca(NO₃)₂ and the calcium chelate contain. Calcium was applied five times at a rate of 4.6 g•m^-2 per month for a total of 23 g•m^-2 Ca.

Throughout the first year of the study there were no leaf color or texture differences between the treatments. Adding Ca to the creeping bentgrass did not increase the concentration of Ca in the leaf tissue (Table 2). This field study is being repeated again in 2000 and more detailed results will be presented next year.

Table 1. Total clipping dry weight (g) and nitrogen (N), calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) concentrations (g•kg^-1) for two grass species grown in a greenhouse during 1998. The grasses were grown on silica sand (S) (pH=7.2), and calcareous sand (C) (pH=8.2). Clipping dry weights are the average total accumulation of clippings over 10 weeks. Nutrient concentrations are from Inductive Coupled Argon Plasma (ICAP) and Total Kjeldahl Nitrogen (TKN) analysis performed on the clippings collected during the first eight weeks. The bottom columns are the General Linear Model Procedure P > F results; and G is the Grass, S is the Sand type, and Trt is the calcium treatment.

Table 2. Nitrogen (N), calcium (Ca), magnesium (Mg), and potassium (K), concentrations (g•kg^-1) for ‘Crenshaw’ creeping bentgrass established on a pure sand-based green (pH=8.2). Results are from the first year of a two-year field experiment. Nutrient concentrations are from Inductive Coupled Argon Plasma (ICAP) and Total Kjeldahl Nitrogen (TKN) analysis performed on the clippings collected immediately before the 4^th and 5^th treatment applications. The table is formed from the averages of the two testing dates.